Circular RNA hsa_circ_0032683 inhibits the progression of hepatocellular carcinoma by sponging microRNA-338-5p

hsa_circ_0000518 stimulates the malignant progression of hepatocellular carcinoma via regulating ITGA5 to activate the Warburg effect

Studies have shown that the abnormal expression of circular RNA (circRNA) is inextricably linked to hepatocellular carcinoma (HCC). Recently, hsa_circ_0000518 (circ_0000518) was discovered in many cancer progressions. However, its function in HCC is still unclear. Through GEO database analysis combined with gene expression detection of HCC related clinical samples and cell lines, we identified that circ_0000518 was abnormally overexpressed in HCC. Cell and animal model experiments jointly indicated that circ_0000518 can stimulate HCC cell proliferation, migration, invasion and suppress apoptosis. Furthermore, we also found that knocking down the circ_0000518 could inhibit the Warburg effect in HCC cells. Mechanistically, circ_0000518 was found to be primarily localized in the cytoplasm, and sponge hsa-miR-326 (miR-326) promoted integrin alpha 5 (ITGA5) expression. In addition, circ_0000518 could enhance the stability of HuR-mediated ITGA5 mRNA, thereby activating the Warburg effect. In conclusion, this study elucidated that circ_0000518 was a cancer-promoting circRNA, which could enhance ITGA5 expression through competing endogenous RNAs (ceRNA) and RNA Binding Protein (RBP) mechanisms, thus facilitating the development of HCC. It provides a meaningful diagnostic and therapeutic target for HCC.

CircFBXW4 Suppresses Colorectal Cancer Progression by Regulating the MiR-338-5p/SLC5A7 Axis

Dysregulated circular RNAs (circRNAs) contribute to tumourigenesis and cancer progression. However, the expression patterns and biological functions of circRNAs in colorectal cancer (CRC) remain elusive. Here, RNA sequencing and bioinformatics analyses are applied to screen for aberrantly expressed circRNAs. The expression of circFBXW4 in CRC tissues and cell lines is determined by quantitative real-time PCR. A series of in vitro and in vivo biological function assays are implemented to assess the functions of circFBXW4. The regulatory mechanisms linking circFBXW4, miR-338-5p, and SLC5A7 are explored by western blotting, dual luciferase reporter assays, and RNA pull-down assays. CircFBXW4 is dramatically downregulated in CRC tissues and cell lines. circFBXW4 downregulation is clearly correlated with malignant features and patient overall survival in CRC. Functionally, ectopic expression of circFBXW4 strikingly impairs the proliferation, migration, and invasion capacities of CRC cells in vitro and in vivo, whereas circFBXW4 knockdown has the opposite effects. Mechanistically, circFBXW4 competitively binds to miR-338-5p and prevents it from interacting with and repressing its target SLC5A7, thus suppressing the progression of CRC. This study reveals the specific critical role of circFBXW4 in inhibiting CRC progression via the miR-338-5p/SLC5A7 axis and provides an additional target for eradicating CRC.

Emerging Role of Circular RNAs in Hepatocellular Carcinoma Immunotherapy

Hepatocellular carcinoma (HCC) is a highly fatal malignancy with limited therapeutic options and high recurrence rates. Recently, immunotherapeutic agents such as immune checkpoint inhibitors (ICIs) have emerged as a new paradigm shift in oncology. ICIs, such as programmed cell death protein 1 (PD-1) inhibitors, have provided a new source of hope for patients with advanced HCC. Yet, the eligibility criteria of HCC patients for ICIs are still a missing piece in the puzzle. Circular RNAs (circRNAs) have recently emerged as a new class of non-coding RNAs that play a fundamental role in cancer pathogenesis. Structurally, circRNAs are resistant to exonucleolytic degradation and have a longer half-life than their linear counterparts. Functionally, circRNAs possess the capability to influence various facets of the tumor microenvironment, especially at the HCC tumor-immune synapse. Notably, circRNAs have been observed to control the expression of immune checkpoint molecules within tumor cells, potentially impeding the therapeutic effectiveness of ICIs. Therefore, this renders them potential cancer-immune biomarkers for diagnosis, prognosis, and therapeutic regimen determinants. In this review, the authors shed light on the structure and functional roles of circRNAs and, most importantly, highlight the promising roles of circRNAs in HCC immunomodulation and their potential as promising biomarkers and immunotherapeutic regimen determinants.

Depletion of circ_0088046 suppressed cell growth and motility of hepatocellular carcinoma via circ_0088046-miR-1299-RTKN2 ceRNA pathway

Circular RNAs (circRNAs) have been verified to be important modulators and therapeutic targets of human hepatocellular carcinoma (HCC). This study aims to explore the role and mechanism of circ_0088046 in HCC progression. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry assays were used to detect the mRNA and protein expression of circ_0088046, miR-1299, Rhotekin 2 (RTKN2), Bax, Bcl-2, E-cadherin and Ki-67. Cell proliferation was investigated by 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell colony formation assay. Cell apoptosis rate was measured by flow cytometry. Transwell migration and invasion assays were adopted to assess cell migration and invasion. The molecular target relationship between miR-1299 and circ_0088046 or RTKN2 were analysed by dual-luciferase reporter assay and RNA immunoprecipitation assay. An animal experiment was conducted to demonstrate the effect of circ_0088046 on tumour formation in vivo. High levels of circ_0088046 and RTKN2, and low levels of miR-1299 were displayed in HCC tissues and cells. Circ_0088046 absence repressed cell proliferation, migration and invasion, but boosted apoptosis of HCC cells. MiR-1299 was a target of circ_0088046 and miR-1299 inhibitor restored circ_0088046 silencing-mediated inhibitory impacts on HCC cell malignancy. MiR-1299 could directly target RTKN2, and overexpressed RTKN2 rescued the suppressive effects caused by miR-1299 mimic. In addition, circ_0088046 silencing constrained tumour formation in vivo. Circ_0088046 contributed to HCC cell malignancy via modulating the miR-1299/RTKN2 axis.

Circular RNAs in hepatocellular carcinoma: biogenesis, function, and pathology

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Both genetic and environmental factors through a multitude of underlying molecular mechanisms participate in the pathogenesis of HCC. Recently, numerous studies have shown that circular RNAs (circRNAs), an emerging class of non-coding RNAs characterized by the presence of covalent bonds linking 3' and 5' ends, play an important role in the initiation and progression of cancers, including HCC. In this review, we outline the current status of the field of circRNAs, with an emphasis on the functions and mechanisms of circRNAs in HCC and its microenvironment. We also summarize and discuss recent advances of circRNAs as biomarkers and therapeutic targets. These efforts are anticipated to throw new insights into future perspectives about circRNAs in basic, translational and clinical research, eventually advancing the diagnosis, prevention and treatment of HCC.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Deciphering STAT3 signaling potential in hepatocellular carcinoma: tumorigenesis, treatment resistance, and pharmacological significance

Hepatocellular carcinoma (HCC) is considered one of the greatest challenges to human life and is the most common form of liver cancer. Treatment of HCC depends on chemotherapy, radiotherapy, surgery, and immunotherapy, all of which have their own drawbacks, and patients may develop resistance to these therapies due to the aggressive behavior of HCC cells. New and effective therapies for HCC can be developed by targeting molecular signaling pathways. The expression of signal transducer and activator of transcription 3 (STAT3) in human cancer cells changes, and during cancer progression, the expression tends to increase. After induction of STAT3 signaling by growth factors and cytokines, STAT3 is phosphorylated and translocated to the nucleus to regulate cancer progression. The concept of the current review revolves around the expression and phosphorylation status of STAT3 in HCC, and studies show that the expression of STAT3 is high during the progression of HCC. This review addresses the function of STAT3 as an oncogenic factor in HCC, as STAT3 is able to prevent apoptosis and thus promote the progression of HCC. Moreover, STAT3 regulates both survival- and death-inducing autophagy in HCC and promotes cancer metastasis by inducing the epithelial-mesenchymal transition (EMT). In addition, upregulation of STAT3 is associated with the occurrence of chemoresistance and radioresistance in HCC. Specifically, non-protein-coding transcripts regulate STAT3 signaling in HCC, and their inhibition by antitumor agents may affect tumor progression. In this review, all these topics are discussed in detail to provide further insight into the role of STAT3 in tumorigenesis, treatment resistance, and pharmacological regulation of HCC.

Down-regulated HSA_circ_0003528 inhibits hepatocellular carcinoma aggressiveness via the miR-212-3p/XIAP axis

Hepatocellular carcinoma (HCC) is characterized by a high mortality rate. Dysregulated circular RNAs (circRNAs) play a vital role in HCC. We aimed to study the role of circ_0003528 in HCC and its fundamental molecular mechanisms. HSA_circ_0003528 was identified through bioinformatics dataset analysis. The binding sites between mRNA and miRNA were predicted using online bioinformatics tools. The interaction between miR-212-3p and X-linked inhibitor of apoptosis protein (XIAP) or circ_0003528 was confirmed through the luciferase reporter assay. RT-qPCR and western blot assays were used to analyze the expression of all miRNAs/mRNAs and proteins. Cellular functions were evaluated using the MTT and TUNEL assays. A xenograft model was established to evaluate the function of circ_0003528 in vivo. Circ_0003528 was dramatically overexpressed in HepG2 and HUH7 cells. However, knockdown of circ_0003528 suppressed the aggressiveness of HCC cells and tumor growth both in vitro and in vivo. Furthermore, binding of miR-212-3p to circ_0003528 and XIAP was verified. Downregulation of miR-212-3p abrogated the effects of si-circ_0003528 on cell viability and apoptosis, and upregulation of XIAP antagonized the functions of the miR-212-3p mimic in HCC cells. circ_0003528 contributes to the development of HCC in vitro and in vivo via the miR-212-3p/XIAP axis. Hence, circ_0003528 knockdown may be a potential therapeutic strategy for HCC treatment.